The present invention relates to the field of fiber optics, and more specifically relates to improvements in connector components and methods for making those improved components.
Fiber optic communication systems send messages in the form of pulses of light along thin strands of transparent material, referred to as fiber optics. One common application for such systems is in carrying digital data between computers in a network or between portions of a large computer. In a typical system, a device referred to as an optical transmitter includes a laser that emits light. The intensity of the light is varied in accordance with the information to be sent. The emitted light is focused on an end of an optical fiber so that the light is transmitted along the fiber. At the other end of the fiber, the light is directed onto a photodetector, which transforms the light into an electrical signal. The electrical signal also varies in accordance with the information being sent. A xe2x80x9cduplexxe2x80x9d system typically uses two fibers in parallel, and has a transmitter and a receiver at each end of the system so that information can be sent in opposite directions along the two fiber optics. The transmitter and receiver at each end typically are combined in a single device referred to as a xe2x80x9ctransceiver.xe2x80x9d Optical communication systems can transmit data at rates many times faster than systems using electrical wires, and offer other advantages.
Typically, the optical fibers are provided in optical cables. The fibers themselves are covered by protective coatings or xe2x80x9csheathing.xe2x80x9d The cable includes one or more individual sheathed fiber optics, covered by an external jacket and may also include components for protecting the cable against physical strain. To set up an optical communications system, cables of this type are connected to optical devices such as transceivers and to one another in much the same way as electrical cables are connected to electronic devices and to one another to set up an electronic system. However, connecting an optical cable requires that the individual optical fibers be precisely aligned with the mating fibers or devices. The optical fibers commonly are as small as 0.125-mm (0.005 inches) in diameter. To connect two fibers end-to-end, the mating ends should be aligned with one another within a few microns, i.e., within hundred-thousandths of an inch, and should be butted against one another with essentially no gaps. Even slight deviation from these tolerances can cause appreciable loss of light transmitted along the fibers and degradation of the signal. Likewise, when an optical cable is connected to a transceiver or other device, the fibers must be precisely positioned relative to the optical elements of the device. Optical cables are provided with devices referred to as xe2x80x9cconnectorsxe2x80x9d which can be engaged with mating connectors on other cables, or with mating features on transceivers or other devices, to align the fibers with the required precision.
One known type of fiber optic connector is a so-called xe2x80x9cMTxe2x80x9d type. The MT connector has a connector housing with a front end and a ferrule movably mounted in the housing. The ferrule is biased by a spring to a forward position. When the ferrule is in the forward position, a front face of the ferrule projects from the housing. A multi-fiber cable extends into the housing. The individual fibers of the cable extend through the ferrule to the front face. The front face of the ferrule, and the ends of the fibers, are polished to form a flat surface. The fiber ends are precisely located within the ferrule. The ferrule also has pin-receiving bores. A male MT-type connector has pins in these bores projecting beyond the front face, whereas a female MT connector has the bores empty. Two cables may be connected to one another by engaging male and female MT connectors with one another so that the pins of the male connector enter the pin receiving bores of the female connector. The ferrules are free to xe2x80x9cfloatxe2x80x9d or move slightly relative to the housing of the connectors and hence are brought into precise alignment with one another by the pins. Also, because each ferrules is free to move rearwardly relative to its housing against the spring bias, the ferrules can be brought into abutting, face to face contact despite tolerances in the housings. These connectors can provide the good connection between the individual fibers of the two cables, with low optical transmission losses.
One type of connector that has been proposed is referred to in the industry as an MT-RJ connector. U.S. Pat. No. 5,926,596 depicts a typical MT-RJ connector. Reference is made to the ""596 patent without admission as to whether or not such patent constitutes prior art against the present invention. As shown in the ""596 patent, a typical MT-RJ connector includes an exterior housing which resembles the exterior housing of the common xe2x80x9cRJxe2x80x9d plug used to connect a home telephone to a wall outlet. The housing has a flexible catch on its exterior. A xe2x80x9cferrulexe2x80x9d is movably mounted within the housing at a forward end of the housing, so that a forward face of the ferrule is exposed to the exterior of the housing. A spring inside the housing urges the ferrule in the forward direction. The ferrule has a pair of fiber bores for receiving two individual fibers of the cable, and a pair of pin holes for receiving alignment pins. A xe2x80x9cmalexe2x80x9d MT-RJ connector has alignment pins permanently disposed in its alignment pin holes, whereas a xe2x80x9cfemalexe2x80x9d MT-RJ connector has empty pin holes. The connectors may be permanently installed on the ends of fiber optic cables by the cable manufacturer. The cable manufacturer positions the fibers in the fiber bores and polishes the ends of the fiber precisely flush with the front of the ferrule.
To connect two cables end-to-end, male and female connectors are inserted into opposite ends of a hollow double-ended socket so that the catches on their housing engage with the socket and the socket physically holds the housings in crude alignment with one another. The pins on the ferrule of the male connector engage the pin holes in the ferrule of the female connector, and hold the ferrules, and hence the fibers, in precise alignment with one another. The springs in the housings urge the ferrules forwardly so that the front faces of the ferrules, and hence the ends of the fibers, abut one another. Devices such as transceivers are equipped with single-ended sockets adapted to receive the housing of a connector. Such sockets are equipped with pins corresponding to the pins of a male MT-RJ connector for engaging the ferrule of a female connector so as to hold the ferrule and hence the fibers of the cable in precise alignment with the device.
Despite considerable effort devoted by the art to development of fiber optic connectors, sockets and related components, there are still needs for further improvements.
There exists a need for further improvement to the housing of an MT-RJ connector that would allow easier insertion and removal of the connector. Currently, the housing of MT-RJ connectors are quite small and do not provide adequate surface area for a technician to grasp the connector. However, any extension of the surface area of the housing or variation in shape must conform to industry standards for these connectors. A connector that is too large may interfere with neighboring connectors or sockets by limiting access to those connectors, as in a network hub or other computer systems employing fiber optics.
There is also a need to improve the latch mechanism to prevent accidental releases of the connector from the socket.
Regarding the socket, a need exists to provide a socket design that allows a technician to visually determine, or by touch, the orientation of the socket to ensure that the connector is rotated to the correct position to have proper alignment of the fiber optics. In a typical MT-RJ connector, there is only one orientation for both the connector and the socket that will properly position the fiber optics. As such, a keyway is provided in the socket with an accompanying protrusion on the connector that matches the keyway. Thus, the connector can only be inserted into the socket in only one way. However, the sockets are quite small and are usually positioned inside a computer or in a space that is crowded with other fiber optic couplers, thus making it difficult for a technician to find the proper alignment of the connector and socket. A visual aid on the outside of the socket would allow a technician to identify the correct orientation of the socket without difficulty.
There also exists a need to improve sockets to prevent the contamination of the optical interface by dust or other particulate matter entering the socket when an end of the socket is open and unoccupied by a cable. Such particulate matter can cause difficulties in making a connection. Also, there exists a need to improve the socket to block light emission from such an unoccupied socket end. If a device is connected to one end of a socket and the other end of the socket is left open, light emitted by the device is sent out into the room environment. The emitted light can cause unpleasant sensations if it impinges on the naked eye. Some occupational and environmental health authorities regard such emitted light as potentially dangerous. Accordingly, it would be desirable if a socket could be provided with some device to block such emissions when the socket is unoccupied. However, any such device should be economical to manufacture and should not interfere with installation of a connector in the socket. Moreover, sockets of this type must fit within limited space set by industry standards. Any emission-blocking device should not make the socket appreciably larger, and should allow the socket to meet industry standards. Taken together, these requirements pose a considerable challenge.
A further need persists to improve the ferrule assembly in the connector. The ferrules of mating connectors must be properly aligned and centered to ensure a proper connection without undue transmission losses. Proper alignment also prevents stubbing of the guide pins when the connectors are mated. Stubbing occurs when one of the ferrules of two mated connectors are off center and the guide pins of the male connector are not inserted into the holes of the female connector. When stubbing occurs, the ferrules are pushed back into the housing of the connector, resulting in a misalignment of the fiber optics and thus no light passing through the coupler.
It would be desirable to provide a connector with the flexibility to allow a field technician to adjust the guide pin placement, depending on field requirements. In some cases, a transceiver or other connector may have a pin placement that does not correspond to the connector to be mated. When this occurs, it would be desirable to adjust the pins of a connector without having to remove and replace the connector from the fiber optic with a new pin configuration. This would save a tremendous amount of time and labor and reduce the down time of the network system. Such a connector should also be reusable after a pin adjustment.
The present invention addresses these needs and provides improvements that can be used in MT-RJ connectors and in similar connectors. The improved connector is described below.
In accordance with one aspect of the invention, a fiber optic connector comprises a housing adapted to hold a fiber optic cable. The housing has a forward direction, upward and downward directions transverse to the forward direction and lateral directions transverse to the forward direction and transverse to the upward and downward directions. The housing includes a main portion having a downwardly-facing bottom surface and the housing further includes a forward portion projecting forwardly from the main portion. The connector is used in an assembly with a generally tubular socket having forward and rearward directions, upward and downward directions transverse to the forward and rearward directions of the socket and lateral directions transverse to the other directions of the socket. The socket defines a bore extending in the forward and rearward directions. The socket also has a downwardly-facing bottom surface. The bore of the socket is adapted to receive the forward portion of the housing in a predetermined orientation relative to the socket so that the directions of the housing are aligned with the corresponding directions of the socket. A latch for holding the housing and the socket together, and a latch release member disposed above the main portion of the housing are also provided. The latch is adapted to release the housing from the socket when the latch release member is depressed toward the main portion of the housing. The bottom surface of the main portion projects downward to or below the bottom surface of the socket when the forward position of the housing is received in the bore. Thus, the bottom surface of the housing main portion is not recessed relative to the bottom surface of the socket. This allows the technician to grasp the housing easily.
Preferably, the bottom surface of the socket and the bottom surface of the main portion of the housing are generally planar. More preferably, the bottom surfaces of both the socket and the housing main portion are substantially coplanar when the forward portion of the housing is received in the bore of the socket.
It is also preferred that the bottom surface of the housing main portion has a pattern of projections and recesses thereon. More preferably, these projections and recesses are in the form of laterally-extending ridges and grooves. The socket and main portion of the housing desirably each have laterally-facing, generally planar side surfaces. The side surfaces of the housing and socket desirably are substantially coplanar with one another when the forward portion of the housing is engaged in the bore. This further facilitates the technician grasping the connector to insert or remove it from the socket. The housing desirably also has ridges and grooves to aid in grasping. The housing for the connector, however, desirably does not extend past the perimeter of the socket, when viewed front to rear. The increase in surface area does not interfere with the ability of the technician to handle neighboring connectors or other devices in proximity to the connector.
The latch release member desirably is resilient and formed integrally with the main portion of the housing. The latch includes an arm projecting forwardly from the latch release member over the forward position of the housing, and a barb projecting upwardly from the arm remote from the latch release member. The socket also has a recess for engaging the barb.
According to another aspect of the present invention, a fiber optic connector assembly comprises a housing adapted to hold a fiber optic cable. The housing has a forward direction, upward and downward directions transverse to the forward direction and lateral directions transverse to the forward direction and transverse to the upward and downward directions as described above. The housing includes a main portion and a forward portion projecting forwardly from the main portion also described above. The housing further includes a resilient latch release member projecting upwardly and forwardly from the main portion of the housing and a latch arm formed integrally with the latch release member and projecting forwardly from the release member above the forward portion. A barb with a rearwardly-facing catch surface projects upwardly from the arm at a forward end of the arm remote from the latch release member. The fiber optic connector further comprises a socket having forward and rearward directions, upward and downward directions transverse to the forward direction of the socket and lateral directions transverse to other directions of the socket. The socket defines a rear face and a bore extending forwardly from the rear face. The socket has a top wall with an interior surface facing downwardly towards the bore. The top wall has a pocket open to the interior surface and an axially-facing catch surface extending to the interior surface. The bore of the socket is adapted to receive the forward portion of the housing and the arm in a predetermined orientation relative to the socket so that directions of the housing are aligned with the corresponding directions of the socket and so that the arm faces toward the top wall and the barb is received in the pocket with the catch surface of the barb confronting the catch surface of the top wall. The top wall defines a ramp surface sloping downwardly in the forward direction of the socket. The ramp surface overlies the arm when the housing is engaged with the socket and rear portions of the ramp surface remote from the engaged catch surfaces are spaced upwardly from the arm. Spacing of the rear portion of the ramp surface from the arm helps to prevent inadvertent release of the catch responsive to vertical forces applied to the connector housing in service. This aspect of the invention incorporates the realization that inadvertent releases of the latch can be caused by engagement between the rear portion of the arm and the socket if the housing is forced upwardly during service. Providing a clearance alleviates this problem.
Preferably, the latch release member includes a beam having a first portion projecting upwardly and forwardly from the main portion of the housing and having a second portion projecting downwardly from the main portion. The beam is preferably flexible at least at the junction between the first and second portions. The beam is desirably formed integrally with the housing, is less than about 1-mm thick and is unreinforced at least at the junction between the first and second portions.
According to a further aspect of the present invention, a socket for receiving a fiber optic connector housing is provided. The socket has forward and rearward directions, upward and downward directions transverse to the forward and rearward directions and lateral directions transverse to the other the directions. The socket defines a bore extending in the forward and rearward directions. The bore has a principal portion and a keyway extending along the top of the principal portion. The keyway has lateral dimensions less than the lateral dimensions of the bore. The socket has an exterior profile including a principal portion having a first width and a top portion having a second width less than the first width. The top portion and the principal portion cooperatively defines a pair of ledges extending axially on opposite sides of the top portion. The principal portion of the bore is disposed in the principal portion of the exterior shape. The keyway extends in the top portion. This aspect of the current invention incorporates the realization that technicians had difficulty in determining the orientation of the keyway of the socket. The ledges provide visual and tactile reference, to the top of the keyway, thus indicating the proper orientation for the connector to be inserted into the socket.
Another aspect of the invention provides a socket for receiving a fiber optic connector housing. The socket has forward and rearward directions, upward and downward directions transverse to the forward and rearward directions and lateral directions transverse to the other said directions. The socket defines a bore having an opening at the rearward end of the housing and extending forwardly into the housing. The housing has a panel mounting portion spaced forwardly from the rear end of the housing. A door and one or more hinges supporting the door on the housing are also provided for pivoting movement about a vertical axis between a closed position in which the door blocks the opening of the bore and an open position in which the door does not block the opening. A spring is also disposed outside of the housing. The door, the hinges and the spring have width and height dimensions equal to or smaller than the width and height dimensions of the panel mounting portion.
Preferably, the housing defines a first indentation at the rearward end of the housing and the hinges include a top hinge disposed in the first indentation. The housing defines a bottom surface at the rearward end of the housing. The bottom surface desirably is recessed upwardly relative to the bottom surface of the panel engaging portion, and the hinges include a bottom hinge overlying the recessed bottom surface. Preferably, the recessed bottom surface extends laterally across the exterior of the housing and the door defines a bottom overhang which projects downwardly beyond the recessed bottom surface. The first indentation may be disposed on one lateral side of the housing and the housing desirably defines a second indentation on the opposite lateral side. The door has an overhang portion which is aligned with the second indentation. As discussed above, the housing may defines a main bore and a keyway having width smaller than said main bore. The keyway may be disposed between the first and second indentations.
The overhanging portions of the door allow the technician to engage the door readily with a finger or tool and to swing the door out of the way during installation of a connector in the socket. To further facilitate this action, it is also preferable that the door has a projection extending rearwardly on a side of the door remote from the hinges, so that the technician can engage the projection to open the door.
The housing desirably has at least two resilient panel extensions projecting outwardly from the housing in vertical directions, lateral directions or both vertical and lateral directions beyond the dimensions of the panel mounting portion. The panel extensions are disposed rearwardly of the panel mounting portion. The panel extensions are inwardly deformable so that the housing can be advanced into a panel and the panel extensions will deform inwardly to pass through an opening in a panel and return outwardly to hold the socket in the panel. The socket may further include engagement projections projecting outwardly from the housing in vertical directions, lateral directions or both vertical and lateral directions beyond the dimensions of the panel mounting portion. The engagement projections are spaced forwardly of the panel extensions so that a panel can be engaged between the engagement projections and the panel extensions. The panel extensions work with the engagement projections to allow the socket housing to be inserted into a hole in a panel and have the housing be secured in the hole. Desirably, each panel extension includes a portion of a lateral wall of the housing. Each such lateral wall has a U-shaped slot bordering such portion of the wall so that each such wall portion forms a tongue connected to the remainder of the wall only at the at the rearward end of the tongue.
In yet another aspect of the present invention, a fiber optic connector includes a housing having forward and rearward directions. The housing has an interior passage extending forwardly and rearwardly. A pair of stops is also provided projecting into the passageway. The stops are spaced apart from one another in a first direction transverse to the forward and rearward directions. The housing has interior guide surfaces bounding the passageway to the rear of the stop surfaces and sloping outwardly away from one another in the rearward direction. A ferrule is further provided having a front end and a rearward portion. At least one fiber bore for holding an optical fiber extending into the ferrule from the front end, and at least one pin-receiving bore parallel to the fiber bore extending into the ferrule from the front end are provided. The rearward portion of the ferrule has a dimension in the first direction greater than the dimension of the opening between the stops. The ferrule is slidably disposed in the housing with the rearward portion disposed to the rear of the stops. The ferrule is movable between a forward position in which the ferrule is engaged with the stops and a rearward position in which the ferrule is disengaged from the stops. Guide surfaces constraining the ferrule in at least one direction transverse to the forward and rearward directions when the ferrule is in the forward position are also provided. The constraint is released due to the slope of the guide surfaces as the ferrule moves rearwardly in the housing. Also provided is a spring biasing the ferrule forwardly against the stops. This aspect of the invention provides a unit that tends to keep the ferrule centered in the connector housing before the connectors are mated, thus facilitating proper alignment when connectors are mated. Stubbing of the guide pins is thus minimized. However, the ferrule can float or move laterally with respect to the housing during mating.
Preferably, the guide surfaces constrain the ferrule in all directions transverse to the forward and rearward directions when the ferrule is in the forward position. More preferably, the housing has upward and downward directions transverse to the axial direction and lateral directions transverse to the axial direction and transverse to said upward and downward directions. The passageway desirably is generally rectangular in cross-section and has vertical walls facing laterally inwardly toward one another and horizontal walls facing upwardly and downwardly toward one another. The guide surfaces desirably include a first pair of guide surfaces extending along the vertical walls and a second pair of guide surfaces extending along the horizontal walls. The ferrule desirably has a forward portion defining the front end of the ferrule and projecting between the stops. More preferably, the stops define rearwardly-facing seating plane surfaces. The ferrule further has forwardly-facing shoulder surfaces engaged with the seating plane surfaces when the ferrule is in the forward position. Desirably, the second pair of guide surfaces include a pair of straight wall regions extending rearwardly from the seating plane surfaces and a pair of sloping wall regions extending from said straight wall regions.
The ferrule may be a molded element having a parting line. The parting line extends forwardly and rearwardly in the body. The body has slots extending forwardly and rearwardly and are aligned with the parting line, whereby the slots provide clearance for the parting line. This aspect of the invention incorporates the realization that in the molding process used to form the ferrule, irregularities may be formed along the parting line. The slots allow a clearance around the parting line to accommodate any such irregularities. This further reduces the possibility of misalignment of the fiber optics or stubbing of the guide pins.
In another aspect of the present invention, a method of providing matable fiber optic connectors preferably comprises the following steps: providing a plurality of terminated fiber optic cable ends, each such cable end having thereon a housing and a ferrule unit resiliently mounted in the housing. Each such ferrule unit has an exposed forward face and the optical fibers of the cable extend to exposed ends at such forward face. Each such ferrule unit further having one or more pin-receiving bores extending rearwardly from such forward face in predetermined locations relative to the exposed ends of the fibers. Each such pin-receiving bore desirably includes a clearance portion adjacent the forward face of the ferrule unit and an interference-fit portion having at least one dimension smaller than the interference-fit portion remote from the forward face. Another step includes selectively making some of the cable ends into male ends or hermaphroditic ends by engaging pins in at least some of the pin-receiving bores of the ferrule units on such ends so that such pins are forcibly engaged in the interference-fit portions of the pin-receiving bores and such pins project beyond the forward face of the ferrule unit. The pin-engaging step is performed while the housings and ferrule units remain in place on the cable ends.
Preferably, the step of making at least some of the cable ends into male ends or hermaphroditic ends includes the step of making such ends male ends by inserting pins into all of the pin-receiving bores of those ends. Desirably, each pin has a groove at a proximal end. The proximal ends of the pins are engaged in the interference-fit portions of the pin-receiving bores. A related aspect of the present invention provides a method of providing matable fiber optic connectors comprising the steps of providing a plurality of terminated fiber optic cable ends. Each such cable end has thereon a housing and a ferrule unit resiliently mounted in the housing. Each such ferrule unit has an exposed forward face and has optical fibers of the cable extending to exposed ends at such forward face. Each such ferrule unit further has one or more pin-receiving bores extending rearwardly from such forward face in predetermined locations relative to the exposed ends of the fibers. Each such pin-receiving bore includes a clearance portion adjacent to the forward face of the ferrule unit and an interference-fit portion having at least one dimension smaller than the interference-fit portion remote from the forward face. At least some of the cable ends are male or hermaphroditic cable ends having pins forcibly engaged in the interference-fit portions of at least some of the pin-receiving bores and projecting beyond the forward faces of the ferrule units. The method further includes converting at least some or the male or hermaphroditic ends to female ends by extracting the pins from the ferrule units of such ends while the housings and ferrule units remain in place on the cable ends.
Methods according to these aspects of the invention provide for field insertion or field removal of the pins and hence allow the technician in the field to mate up any cable end to any device or mating end, without regard to whether the cable ends are originally male or female.
Another aspect of the present invention discloses a terminated fiber optic cable end comprising a fiber optic cable including one or more fibers, a housing mounted on an end of the cable, and a ferrule unit resiliently mounted in the housing. Each such ferrule unit has an exposed forward face and has optical fibers of the cable extending to exposed ends at such forward face. Each such ferrule unit further has one or more pin-receiving bores extending rearwardly from such forward face in predetermined locations relative to the exposed ends of the fibers. Each such pin-receiving bore includes a clearance portion adjacent to the forward face of the ferrule unit and an interference-fit portion has at least one dimension smaller than the interference-fit portion remote from the forward face.
Preferably, the terminated fiber optic cable ends further comprise pins in the pin-receiving bores of the ferrule unit. Each of the pins has a proximal end engaged in the interference-fit portion of one of the pin-receiving bore. Each pin has a distal end projecting through the clearance portion of the pin-receiving bore beyond the forward face of the ferrule unit. More preferably, the proximal end of each pin includes a tapered proximal tip, a groove encircling the pin, and a cylindrical portion between the tapered proximal tip and the groove. Each pin also includes a cylindrical main region extending from the groove toward the distal end of the pin. Preferably, the ferrule unit includes a ferrule defining one or more fiber bores holding said fibers. The ferrule also defines the clearance portions of one or more pin-receiving bores. The ferrule unit also includes a pin retainer formed separately from the ferrule and defining interference fit portions of one or more pin-receiving bores. Alternatively, the pin retainer may comprise blind holes into which the pins are inserted.
Desirably, the pin-retainer has a slot extending to each interference-fit portion so that the interference-fit portion of each pin-receiving bore can expand to accommodate insertion and removal of pins. The ferrule unit desirably includes two pin-receiving bores and two fiber bores, the pin-receiving bores and fiber bores being disposed in a common plane. The pin retainer desirably has a central opening in the common plane, where the fibers pass through the central opening. Preferably, the pin retainer has an entry slot extending transverse to the common plane. The ferrule has a rear face and a central opening extending into the ferrule from the rear face in the common plane. The ferrule also has a front wall defining a front face of the ferrule unit. The fiber bores of the ferrule extend through the front wall to the central opening of the ferrule. The cable end desirably further comprises a hollow tubular ferrule plug having front and rear ends and a central passageway extending between such ends. The front end of the ferrule plug is disposed in the central opening of the ferrule. The rear end of the ferrule plug is disposed in the central opening of the pin retainer. The ferrule plug maintains the pin retainer in alignment with the ferrule. Also preferably, the cable is a ribbon cable that includes a pair of buffered fibers side-by-side. The ribbon cable extends into the central passageway of the ferrule plug. The cable includes a pair of fibers each having an outer buffer and an inner buffer. The outer buffers of the fibers terminate just to the rear of the ferrule plug, with portions of the fibers covered by the inner buffers extending into the central passageway. The outer buffers of the fibers have diameters larger than the height of the central passageway in the ferrule plug, whereby upon rearward movement of the ferrule, the ferrule plug will bear on the outer buffers of the fibers to minimize flexing of fibers.
The cable end may further comprise a spring engaged between the housing and the pin retainer biasing the pin retainer forward relative to the housing to thereby maintain the pin retainer in engagement with the ferrule and bias the entire ferrule unit forwardly relative to the housing. Desirably, the pin retainer has a rear surface and a recess in the rear surface. The spring may be a coil spring encircling the fibers of the cable and engaged in the recess.
In a related aspect of the present invention, a method of making a terminated fiber optic cable end comprises the following steps. Assembling a ferrule having a rear surface, a central passageway open to the rear surface, a front wall, one or more fiber bores extending through the front wall to the central opening and pin-receiving bores extending from the front wall to the rear surface, with a ferrule plug having a central passageway so that the ferrule plug is received in the central opening and the ferrule plug projects rearwardly from the rear surface of the ferrule. Assembling one or more optical fibers of a cable with the ferrule so that each such fiber extends through the passageway of the ferrule plug and through one of the fiber bores in the ferrule, and fastening the fibers to the ferrule. Assembling a pin retainer with the plug and ferrule to form a ferrule unit. The rearwardly-projecting portion of the ferrule plug engaging in a central opening of the pin retainer. The ferrule plug holds the pin retainer in alignment with the ferrule so that pin-receiving bores in the pin retainer are aligned with pin-receiving bores in the ferrule.
Preferably, the method further comprises the step of placing the pin retainer on the fibers remote from the ferrule and plug so that the fibers extend through the central opening of the pin retainer. The step of assembling the pin retainer to the ferrule and plug includes the step of sliding the pin retainer forwardly along the fibers to the ferrule and plug. More preferably, the step of placing the pin retainer on the fibers includes the step of passing portions of the fibers remote from the ends of the fibers through an entry slot in the pin retainer into the central opening of the pin retainer. Desirably, the method further comprises the step of assembling a housing and a spring to the ferrule unit. The method described above allows a technician to insert and withdraw the guide pins without having to remove or replace the entire connector.